The invention relates to a regulator as set forth herein. A regulator is already known as set forth in U.S. Pat. No. 4,388,913, wherein a shaft with a throttle member is mounted in a cover connected to a servomotor and inflow and outflow connection pieces for the medium to be controlled are formed on the cover. A disadvantage of this arrangement is that during assembly of the regulator, it is necessary to determine in advance the disposition of the inflow and outflow connection pieces with respect to one another, more particularly whether they should be in alignment with one another, parallel to one another, at right angles to one another or in some other arrangement. These types of regulators are used to control the idling speed of an internal combustion engine and, accordingly, it is advantageous that they should be readily interchangeable and that they can be mounted in narrow places in the engine of the vehicle. It is also advantageous to be able to change the disposition of the inflow and outflow connection pieces.